1. Explain what causes antigenic drift and describe how it changes the virus. 2.
ID: 274627 • Letter: 1
Question
1. Explain what causes antigenic drift and describe how it changes the virus.
2. Explain how reassortment causes antigenic shift and describe how it changes the virus.
3. Which is more likely to cause a pandemic: antigenic drift or antigenic shift? Explain.
4. Which two types of animals are thought to have been hosts to the reassorted influenza viruses that led to the deadly 1918 fly pandemic?
5. Would you predict that RNA viruses or DNA viruses evolve resistance to antiviral drugs more quickly? Explain your answer.
Explanation / Answer
Please find the answers below:
Answer 1: Antigenic drift refers to alteration in the viral genome leading to mutations which cause change in the antibody-binding site of the antigen. As a result, the virulence of the virus gets changed as it cannot further bind to the same antibody. Hence, the infected host system fails to develop an immune response against such virus and the virulence increases.
Answer 2: Antigenic shift refers to the recombination of two viral genomes to alter the original genome of either or both of them so that the virulence of the viral particles involved changes. This change in virulence is not identified by the infected host system, hence the virulence of the viruses increases, causing elevated pathologies. Most of these changes take place due to faulty replications and errors occuring during replication and hence accumulation of mutations. Other major reason for these observations is the presence of different DNA or RNA fragments from different viruses hence causing horizontal gene transfer.
Answer 3: Antigenic shift is more likey to cause a pandemic since it encompasses the virulence of more than one viruses.
Answer 4: The 1918 Spanish flu pandemic was a result of antigenic shift between two viruses i.e. H1N1 influenza flue viruses. These viruses underwent antigenic shift and caused a pandemic which ended with either death of the infected hosts or eventual development of immunity.
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